Load equalizing antennas

ABSTRACT

A system and method for equalizing traffic between antenna beams is described. Aspects of the system and method may vary the beam widths to attempt to equalize traffic based on non-real-time communications and/or non-real-time communications.

BACKGROUND

1. Technical Field

Aspects of the present invention relate to antennas. More particularly,aspects of the present invention relate to modifying beams from antennasto maximize throughput through a network while maintaining quality ofservice requirements.

2. Related Art

Mobile operators and suppliers constantly search for ways to respond tothe increasing demand for ubiquitous mobile services. Mobile operatorsadjust a network's architecture so that they can introduce new higherspeed technologies quickly, while suppliers are working to devise waysfor improving the capacity of their wireless products. Current trendsindicate:

-   -   a. Mobile operators have embarked on using wireless local area        network (WLAN) technologies to cover hotspots (e.g., airports,        shopping malls, etc.) within their cellular networks, and WLANs        are already the prevalent means of providing mobile services        within large enterprises.    -   b. Wireless suppliers are exploring adaptive array antenna        (dubbed as either “smart” or adaptive antenna) technology as a        promising technique for increasing the capacity of their        cellular and WLAN products. A “smart” antenna may include an        array of radiating antenna elements where the smart antenna        radiation patterns, i.e., the smart antenna beams, as well as        the directions of these beams may be altered by adjusting        relevant parameters (e.g., amplitude and relative phase) on        different array elements. Since each beam of a smart antenna has        a distinct carrier frequency, and represents a distinct physical        channel, the terms “beam” and “frequency channel” are used        herein interchangablely.

The current approaches are cumbersome. They do not dynamically adaptdirections of frequency channels relevant to at least one of locationsand traffic characteristics.

Conventional analytical beam forming techniques usually adjust/controlthe relevant parameters of a smart antenna such that the signal to noiseand interference ratio (SNIR) of each frequency channel is minimized,and its capacity is maximized. The prevalent “optimality” criteria forbeam forming techniques are the minimum mean square error (MMSE), andleast square (LS) techniques. These techniques use optimal filteringtheory to devise a recursive spatial filter that minimizes the square ofthe difference between the antenna array output and locally generatedestimate of the desired signals of subscribers (i.e., a local referencesignal) at the transceiver. The MMSE and LS techniques require that thetransceiver have either a-priori knowledge or an estimate of the desiredsignals of subscribers. These estimates are usually obtained usingmethods such as periodic training sequences, decision directedadaptation, etc. However, they do not dynamically address trafficconcerns or locations.

SUMMARY

Aspects of the present invention relate to allocating beams to provideimproved service to mobile users as their needs change, thus addressingone or more issues with conventional techniques.

BRIEF DESCRIPTION

FIG. 1 shows a process for equalizing load among beams in accordancewith aspects of the present invention.

FIG. 2 shows an illustrative example of an antenna controller inaccordance with aspects of the present invention.

FIG. 3 shows a graphical representation of beam widths being modified inaccordance with aspects of the present invention.

FIG. 4 shows a process for equalizing load among beams in accordancewith aspects of the present invention.

FIGS. 5 and 6 show graphical representations of beam widths beingmodified in accordance with aspects of the present invention.

FIG. 7 shows an illustrative example of a system architecture inaccordance with aspects of the present invention.

FIG. 8 shows a data structure of a user data object in accordance withaspects of the present invention.

FIG. 9 shows signal exchanges in accordance with aspects of the presentinvention.

DETAILED DESCRIPTION

Aspects of the present invention relate to controlling beams to loadbalance frequency channels. Aspects of the present invention may be usedin conjunction with one or more databases that contain information onthe locations and types of services of the users.

Aspects of the present invention may use present uplinks between accesspoints and mobile terminals that recognize the start of frames. Variousapproaches may be used including strictly synchronous technologies(e.g., Bluetooth, CDMA) and not as strictly synchronous technologiesincluding explicit interactions between 802.11 access points and mobileson the uplink that provide relevant framing. At least one advantage mayinclude, when using aspects of the present invention in conjunction witha “packet steering” approach on the uplink, reducing power consumptionof the mobiles without any degradation in the overall throughput of theantenna system.

The following describes aspects of the present invention that attemptsto increase throughput while satisfying the QoS requirements ofreal-time services (e.g., voice) of smart antenna systems (WLAN andothers) whose controller entity may be connected to a database thatcontains information on the locations and type of services of the users.

Referring to FIG. 1, aspects of the present invention may be describedas a process that divides (step 100) time into fixed frames of length T.In step 101, the process divides each time T into a real-time cycle, andending with a non-real-time one. Next, the process uses theusers'locations and relevant information (e.g., capacity, service type)about their sessions to select (step 102) the beam-widths to equalizeloads of beams during the real-time and non-real time cycles.

Aspects of the invention may be used with systems that have or mayobtain a-priori knowledge of each user location, i.e., (r_(i) andθ_(i)), as well as the user's type of service, and updates its databasedynamically as the users move around. Here, r_(i) is the distance of thei-th user from the array antenna, and θ_(i) its azimuthal angle. As oneexample, the session manager (e.g., SIP server) may provide type ofservice information to a smart antenna controller upon receiving sessionset-up and disconnect requests (i.e., “INVITE” or “BYE” messages).Various conventional approaches exist to determine a mobile's locationand are not addressed in detail here. For instance, in mobile operatornetworks, one can easily obtain location information via the globalpositioning system and ranging or hyperbolic position algorithms.

Here, a smart antenna system is expected to provide N distinct frequencychannels, i.e., it has N beam-formers (for instance 3 or 4beam-formers). The maximum, ω_(max), and minimum, ω_(min) feasiblevalues of beam-widths are known (for instance, values such asω_(min)=15° to ω_(max)=80° may be realized). The system is also expectedto support both types of handoff (i.e., mobile assisted hand-off (MAHO)or network assisted hand-off (NAHO)).

The WLAN or other network may support at least one of real-time (e.g.,voice) and non-real-time (e.g., best effort data) services. The loadsmay or may not be symmetric. The network may further exert admissioncontrol on real-time services at the session set up time to properlylimit the number of simultaneous real-time sessions in the WLAN environ.In general, the network may exert admission control on all sessionsexcept those transporting best effort data traffic. Here, the equivalentcapacity of a session may be the estimated amount of capacity that anetwork should allocate to a session so that the QoS requirements of thesession are met.

FIG. 2 shows an illustrative model of a smart antenna system (for usewith WLAN or other networks). The system includes antenna controller 201receiving both real-time 202 and non-real-time 203 inputs. The systemmay have N queues 204-206 with N parallel servers 207-209 providingsupport for the two types of customers, i.e., real-time andnon-real-time packets. The packets of each user may be stored on eachuser's mobile terminal.

This modeling of the system as a single distributed queue with multipleservers reflects the fact that the actual service time of a packetservice is sum of the media access time and its transmission time.

The N parallel servers 207-209 model the N frequency channels of theWLAN smart antenna. The actual service time of a packet equals thewaiting time for access to the channel plus the time it takes totransmit the packet itself. For instance, in 802.11, whenever a mobilehas a packet, its MAC layer may send an RTS (request to send frame)asking for “permission” to send its packet. The customers in each queuerepresent packets of the user population who fall within that frequencychannels coverage. In FIG. 2, the service time includes the elapsed timefor channel access and packet transmission. Thus, a single queue modelfor each frequency channel is adequate even though on the uplink userspackets actually reside in mobiles'buffers that are distributed over thecoverage area of the frequency channel. To this end, additional queueapproaches may be used.

The antenna controller 201 uses users'locations (211) and relevantinformation about their sessions such as the desired capacity of asession and its service time (212) to partition the user population,through adjustments in directions of antenna beams, into N subset that“maximize” the throughput of the system, while satisfying quality ofservice (QoS) requirements of real-time services, e.g., stringent boundson the delay and jitter of real-time (e.g., voice) packets.

To satisfy the QoS requirements of real-time services, the real-timetraffic may or may not be segregated (virtually, not necessarilyphysically) and may have either pre-emptive priority over non-real-timetraffic or receives a periodic service through scheduling.

Also, to maximize the throughput of a queuing system but with only oneclass of packets, it is helpful to keep the servers as busy as possible.

The following describes the antenna system controller first in view ofnon-real-time services then addresses real-time services. Since aspectsof the described controller distribute the user's traffic load acrossthe frequency channels relatively equally, the controller is referred toas a “load equalizer” or “spatial load equalizer.”

Real-Time Services and Non-Real-Time Services

Spatial Load Equalizer

First, systems with only non-real-time services are addressed. Here, forinstance, WLAN environment only supports only non-real-time servicesthat have no delay requirements.

To “maximize” the smart antenna throughput and ensure that it is equallylikely to have a packet or more in each queue, waiting for transmissionon each frequency channel, the controller should partition the userpopulation among the N frequency channels such that the traffic load onthe frequency channels are relatively equal, and the beam-widths of allfrequency channels are in the admissible range for the antenna array.

If the total number of ongoing sessions is U, and the equivalentcapacity of k-th session is C_(k) bps, then the controller maydistribute the ongoing sessions into N neighboring regions/zones suchthat each of the regions contains approximately one-N-th of the totaltraffic load, i.e.,$S = \left\lceil \frac{\sum\limits_{i = 0}^{U - 1}C_{i}}{N} \right\rceil$bps, where ┌z┐ represents the smallest integer that exceeds Z. Thispartitioning process may carried out only based on the azimuthal anglesof users location because there is only one type of service and usersappear in the location database of the smart antenna (provided they arewithin the antenna range). In general, partition of the coverage areasuch that each region/zone contains exactly one-N-th of the totaltraffic load, i.e., S bps is impractical because each region/zone mayonly contain neighboring users, and sessions may have differentequivalent capacities. Thus, instead of looking for strict equality inregions/zones'loads, the approach described herein opts for a spatialload equalizer (i.e., zoning scheme) that distributes the traffic loadrelatively equally among the regions/zones.

The following describes a process for the spatial load equalizer. First,the equalizer starts with packing neighboring users/terminals in the1^(st) region/zone until either the load of the 1^(st) region/zoneexceeds one-N-th of the total traffic or the resulting beam-widthexceeds ω_(max). This is shown by the allocation of mobile users in arc301 defined by the beam width ω₀.

Next, the spatial load equalizer continues with assigning the remaining(i.e., not a member of the 1^(st) region/zone) neighboringusers/terminals to the 2^(nd) region/zone until either the load of the2^(nd) region zone exceeds one-(N-1)-th of the total load of theterminals that has not been assigned to the 1^(st) region. This is shownby users in arc 302 with beam width ω₁.

Next, the spatial load equalizer continues with assigning the remaining(i.e., not a member of the 1^(st) and/or 2^(nd) regions/zones)neighboring users/terminals to the 3^(rd) region/zone until either theload of the 3^(rd) region zone exceeds one-(N-2)-th of the total load ofthe terminals that has not been assigned to the 1^(st) and 2^(nd)regions or the resulting beam-width exceeds ω_(max). This is shown hereby users in arc 303 with beam width ω₂.

This process continues until all N regions or zones are designated.

The width and direction of each beam is set such that it covers one ofthese regions/zones, and its beam direction points to the azimuthalcenter of the region.

The spatial load equalizer may be realized with various algorithms thatsort the users in view of capacity needed and/or location. For instance,a quick sort algorithm among others may be used. A quick sort algorithmcreates a list of ongoing sessions in the descending order of theazimuthal angles of their users. The spatial load equalizer assignsneighboring sessions to a zone/region until either the total load of thezone exceeds S or the resulting beam-width exceeds ω_(max). Assumingthat the azimuthal angle of i-th session's user location is θ_(i), andthe beam-width of the j-th frequency channel is ω_(j), the pseudo codeof the spatial load equalizer may be represented follows:

Call the quick sort algorithm to create a list of the sessions in thedescending order of their azimuthal angles, θ_(U-1), θ_(U-2), . . . θ₀,where θ₀≧θ₁≧ . . . ≧θ_(U).${{{Set}\quad S} = \left\lceil \frac{\sum\limits_{i = 0}^{U - 1}C_{i}}{N} \right\rceil},{\varphi = \theta_{0}},{\omega = 0},{{load} = 0},{{{{and}\quad L} = 0};}$for (j = L, j < N) { if(L != 0) L = L + 1; for ( k = L, k <U) { load =load + C_(k); ω = φ θ_(k); $\begin{matrix}{{{{if}\quad\left( {\left( {\omega \geq \omega_{\max}} \right)\bigvee\left( {{load} \geq S} \right)} \right)\quad L} = k};} \\{{break};}\end{matrix}\quad$ { if (ω ≦ ω_(max)) ω_(j) = ω; else { ω_(j) = ω_(max);L = L − 1; } load = 0; $\begin{matrix}{{\varphi = {\theta_{0} - {\sum\limits_{i = 0}^{j}\omega_{i}}}};} \\{S = \left\lceil \frac{\sum\limits_{i = {L + 1}}^{U - 1}C_{i}}{N - j - 1} \right\rceil}\end{matrix}\quad$ }

First, if a smart antenna is capable of forming beams of arbitrary widthin the range of (0-π], designated neighboring “load-equalized”regions/zones should not overlap. However, in practice, when the loadequalization algorithm/heuristic designates a region/zone whosebeam-width is smaller than ω_(min), an antenna that directs a beam withwidth of ω_(min) to this zone that will overlap with neighboring zones.In other words, if the traffic density at an area is high, this approachmay partition the coverage area into narrower non-overlapping zoneswhose realization in practice results in directing multiple overlappingbeams to the heavy traffic area.

Second, as soon as the location database is updated, the controllerupdates the partitioning accordingly and adjusts the beams directionsand beam-widths such that traffic load is almost equally distributedamong the N frequency channels. Needless to say when the load equalizeradjusts the smart antenna beams, it may force some users to hand-offeven though they may have not moved at all and their locations may nothave changed.

-   -   a. In a WLAN supporting NAHO, the network controller informs the        mobile in advance so that it initiates the process for handing        off to the target frequency channel. In general, this early        warning feature of the NAHO scheme should result in lower        hand-off delay, and better performance.    -   b. However, in a MAHO only environment such as IEEE 802.11, the        load equalizer does not always operates correctly because when        the load equalizer adjusts the beams, and directs a current        serving beam (frequency channel) away from a mobile terminal        (say terminal A) that has not moved since the last beam        adjustment, the following two distinct scenarios can occur:        -   i. The adjustment of the beam results in the drop of the            received signal strength at terminal A below the hand-off            threshold. In this case the load equalizer operates            correctly because the MAHO mechanism of the mobile detects            the change of the beam (channel) in the standard way as if            it has moved from one beam (channel) to another, and invokes            the hand-off process.        -   ii. The adjustment of the beam does not result in drop the            received signal strength at terminal below the hand-off            threshold. In this case the MAHO mechanism does not invoke a            hand-off process because the quality of reception is still            acceptable. Thus, without an additional instruction from the            access point, terminal A does not hand-off to the            neighboring beam (channel), notwithstanding the fact that            the load-equalizer expects it to do so. Thus, in a MAHO only            (e.g., an IEEE 802.11) environment, the access point needs a            mechanism to instruct terminal A to hand-off to the            neighboring beam as the load-equalizer expects.

The implication of the latter scenario is that a MAHO environment (e.g.,IEEE 802.11) also requires a NAHO capability that allows the loadequalizer to unequivocally inform those mobiles that are affected by there-configuration of beams. To ensure correct operation of the loadequalizer, the MAHO and NAHO schemes may be used as follows:

-   -   a. The access point uses the NAHO scheme to inform those        terminals that are re-assigned to a different beam as a result        of latest beam re-configuration.    -   b. The terminals continue to use the MAHO for hand-off as they        move across the beams themselves.

The next question is what protocol does the access point use for itsNAHO mechanism informing the affected mobiles about beam re-assignments.Since the cause of the beam re-assignment is access pointreconfiguration, it may use network management protocol, i.e., SNMP inan IP environment, to instruct the affected mobiles to hand-off to a newbeam/channel. The detail specifications of the NAHO hand-off protocol isnot part of this disclosure. Alternatively, one can invoke lower layerprotocols to perform the required NAHO process. The general approach ofthe NAHO hand-off process is as follows:

-   -   a. When the load-equalizer reconfigures the beams, it will send        a SNMP SET message to all mobiles that are re-assigned to new        beams to inform them about their new frequency channel        identifiers, i.e., SET FREQ_CHANNEL “new channel ID”. Upon        reception of the SET message, the mobile SNMP agent checks and        updates the MIB and forces hand-off to the new channel. The        advantages of this scheme are that:        -   i. It uses the standard SNMP protocol for performing the            NAHO process; has minimal impact on the mobile hardware,            i.e., a register for recording the beam/channel identifier;            does not need any new protocols, and can easily be disabled            when necessary.    -   b. Its main disadvantage is that:        -   i. It requires a running SNMP daemon, and its supporting MIB            on the mobile. The presence of an active SNMP daemon on the            mobile increases the power consumption of the mobile and            takes up part (16-32 MB) of the mobile disk (or memory in            PDAs). The notebooks can easily support these requirements.            In principle, The PDAs can also support them, however, one            may develop “new” link layer NAHO solutions for the PDAs            that takes up much less memory space.

Third, regardless of differences in the actual loads of resulting zones,the “load-equalizing” approach primarily assigns contiguous users andtheir sessions to a zone to ensure smallest possible beam-width andmaximum possible range extension even though non-contiguous distributionof users may result in a less difference among the loads of eachregion/zone.

Fourth, a user may have several simultaneous ongoing sessions. When sucha user has only one interface, the load-equalizing algorithm may assignall sessions of this user to one of the frequency channels, even at riskof increasing the “equalization” error (that is intentionally making thefrequency channels unequal).

In a special case where all users have identical non-real-time sessions(i.e., equivalent capacity of all sessions are identical), theload-equalizer may partition the coverage area of the smart antenna intoN regions/zones such that each region with “equal” session populations,i.e., each frequency channel serves almost 1/N of the sessions. Morespecifically, if the total number of ongoing session is U, and U=(MN+r),and assuming that the equivalent capacity of k-th session is C_(k)=1 forall 0≦k<U, in the pseudo-code of the load equalizer algorithm, theresult is a zoning that distributes these sessions into N neighboringzones such that r of the zones contains M+1 sessions, and the remaining(N−r) zones each have M sessions.

FIG. 3 in summary provides the behavior of the spatial load equalizer ina WLAN smart antenna with N=3 frequency channels and U=14=4N+2 users,where each user has an ongoing best effort data session. The solidoutgoing lines show the boundaries of the frequency channels withbeam-widths of ω₀, ω₁, and ω₂, and the dotted lines depict theirdirections.

The described spatial equalizer may determine the beam-widths in a WLANenvironment that supports real-time and non-real-time servicesconcurrently as well. The spatial equalizer performance is acceptable ifthe load of ongoing real-time sessions in each frequency channel (orbeam) does not exceed the maximum real-time load that it can support.However, if the load of real-time sessions exceeds the maximum that achannel can support, then the QoS requirements of these sessions may notbe satisfied. The system may or may not then use only locations ofreal-time users/sessions to adjust the antenna beams. This approach maysatisfy the QoS requirements of the real-time sessions, though it maydegrade the performance (e.g., throughput, packet loss) of thenon-real-time services because it may result in skewed distribution ofnon-real-time sessions across the beams. The following describes anotherapproach to addressing multiple classes of service.

Temporal-Spatial Load Equalizer

The temporal-spatial load equalizer may be a time-division variant ofthe spatial load equalizer that time-shares the smart antenna systembetween the real-time and non-real-time services such that thethroughput is “maximized” and the QoS requirements of the real-timeservices are satisfied. The temporal-spatial load equalizer divides thetime into equal frames of size T, where every frame comprises areal-time and a non-real-time cycle. During the real-time cycle, onlyreal-time sessions that have packets can transmit. Similarly in thenon-real-time cycle only sessions with non-real-time services can sendpackets. During each real-time (or non-real-time) cycle, the behavior ofthe temporal-spatial equalizer is similar to that of a spatial loadequalizer that supports only real-time (or only non-real-time) sessions.In other words, during the real-time (or non-real-time) cycle, itdistributes the real-time (or non-real-time) sessions into Nregions/zones whose traffic loads are relatively equal, and tailors thebeam-widths and directions of the frequency channels to theregions/zones.

The frame size T is usually equal to the time it takes the slowestreal-time application to generate a packet on the session. For example,for a voice application software that generates a voice packet every 20ms, 40 ms, or 80 ms, T may be set to 20 ms, 40 ms, or 80 ms for theenvironment in which the voice application software is used.

Specifically, assuming that the mobile stations and the smart antennacorrectly recognize the start of the frames (if and when necessary),i.e., having consistent framing structure across the access point andmobiles, the temporal-spatial load equalizer operates as follows:

-   -   a. At the beginning of each frame, i.e., every T seconds, it        computes two sets of beam-widths and directions, one for voice        real-time cycle (i.e., considering only real-time sessions), and        the other for non-real-time cycle (i.e., considering only        non-real-time sessions) in step 401.    -   b. Adjust the beams in accordance with the real-time cycle in        step 402.    -   c. Continue the real-time cycle until all mobiles have sent        their all their real-time packets in step 403.    -   d. On the uplink, the system determines if during the real-time        cycle all frequency channels remain silent for at least an        interval (for instance, (2τ+μ) sec, where 2τ is the round trip        propagation delay on a frequency channel, and μ is the service        (access plus transmission) time of a real-time packet on a        frequency channel) in step 404.    -   e. If no from step 404, the system waits until the interval has        passed.    -   f. If yes from step 404, then in step 405 the temporal-spatial        load equalizer starts the non-real-time cycle and continues it        to the end of the frame in step 406.

Specifically, the controller re-adjusts the antenna beam-widths anddirections such that the load of non-real-time sessions is equallydistributed among them. The downlink may wait for an interval to pass aswell. However, on the downlink an optimization may be realized in thatthe controller may start the shift to the non-real-time cycle as soon asthe smart antenna has depleted the real-time services buffers.

On the uplink, the preceding algorithm requires that the mobiles and thesmart antenna system correctly identifying the start of the frames.Otherwise, on the uplink, the temporal-spatial load equalizer may notoperate properly because users are distributed across the media and haveno single reference for the start of a frame, or different cycles withina frame. However, there is no need for strict framing on the downlinkbecause the antenna itself knows the start of a frame or its cycles, andmobiles'receivers pick up the signal when they receive the signal. Twoapproaches may be used for ensuring consistent framing structure acrossthe access points and the mobiles on the uplink,

-   -   a. strict synchronization between the access points and the        mobiles, and    -   b. explicit messaging/interaction between the access point and        mobiles for announcing the start of frames.

Strictly synchronous technologies such as Bluetooth, CDMA) automaticallyprovide consistent framing structure across the access point andmobiles. However, the synchronization on the uplink may create an issuefor 802.11b WLAN because the IEEE 802.11b specifications do not providemeans of such a strict synchronization between the access point andmobiles. Bluetooth Masters (analogous to APs in WLANs) in fact, do havestrict synchronization with Slaves (analogous to mobiles in WLANs), andthey do know when each slave will transmit and do know whether eachSlave is real-time (e.g., voice) or non-real-time (e.g., data). [49 ]There are at least two ways to deal with the 802.11b issue. The firstsolution is the use of a polling mechanism in the smart antenna systemthat determines which user has the right to transmit. This approach isanalogous to the Point Coordination Function (PCF) specified in thespecifications of the 802.11 media access control (MAC) scheme. Theadvantage of this approach is that it allows contention free voice cycleand potentially increases the number of simultaneous voice sessions perfrequency channel. In a nutshell, this addition to 802.11 MAC providesmeans of four classes of priorities for users packets and an enhancedpolling mechanism similar to the PCF that is dubbed as hybridcoordination function (HCF) in this specifications. Preliminaryperformance evaluation studies show that “the HCF provides means ofdelivering time-bounded traffic, but requires all stations within therange of the HC (Hybrid Coordinator) to follow its coordination.”

In the absence of strict synchronization, one can use explicit messagingbetween the access point and the mobiles to provide a consistent framingstructure on the uplink beam. In this approach, the access pointperiodically sends announcement messages to inform the mobiles about thestart of a new frame. Having announcement messages, the access point mayalso opt for using it to also inform the mobiles about the end of thereal-time (start of non-real-time) cycle within each frame. This use ofannouncement messages for informing mobile about the end of thereal-time (start of non-real-time) cycle may improve the throughput ofthe system on the uplink because it reduces the silence between thecycles by τ seconds. A start of frame announcement message is an 802.11MAC_PDU whose 2 byte Control Field are encoded as follows:

-   -   a. Protocol version: 00, for all frames    -   b. Type: 01, i.e., control MAC_PDU for both START/END    -   c. Subtype: 0000 for START, and 0001 for END    -   d. The remaining bits of the Control field are ignored

This approach introduces negligible additional signaling overhead, andits START/END control MAC_PDUs do not require acknowledgements by themobiles because their payloads are null, and the 4 byte long FCS fieldof the MAC_PDU protects its 2 byte long control field.

Some have proposed an adaptive antenna that measures the aggregatetransmission rate of users over its frequency channels and adapts theirbeam-widths such that the sum of beam-widths of all frequency channels(i.e., the coverage area) remains constant; the beam-width of thechannel with highest traffic is narrowed a certain amount (say λdegrees), and the beam-width of the channel with lightest traffic iswiden the same amount (i.e., λ degrees); and the beam-widths of otherfrequency channels remain constant. At least one of the followingdistinguishes a load equalizing smart antenna from the adaptive antennascheme as described above in that a load equalizing smart antenna:

-   -   a. adapts not only to the aggregated traffic rate but also        users'locations and service types;    -   b. time-shares the antenna between real-time and non-real-time        services in a cyclic manner to virtually segregate these        services, and reduce the adverse effect of non-real-time        services on the performance of their real-time counterparts;    -   c. distributes the traffic load of each service class (e.g.,        real-time) almost equally across the frequency channels during        the class's cycle in each frame to “fairly” improve the QoS for        all users; and    -   d. tracks users'traffic and locations dynamically and does not        always insist on continuously covering a nominal pre-determined        geographic area, though it periodically adjusts its beams to        sweep the whole nominal coverage area of the smart antenna, and        pick up all users who are active there.

Assuming that the system supports only identical voice services andidentical best effort data services, FIG. 5 shows an illustrativeexample with N=3 frequency channels, with five (depicted as concentricrings) of its fourteen users have voice sessions, while the remainingnine are using data sessions. Since all voice sessions are identical,the equivalent capacity of a voice session is unity, i.e., C_(k)=1 forall sessions, to arrive at FIG. 5 for the beam-widths of the frequencychannels, ω₀, ω₁, and ω₂, during the voice cycle at the beginning of aframe. FIG. 6 shows the same mobile terminals during a non-real-timecycle of the frame.

In FIG. 5, the three beams cover primarily the real-time mobileterminals. Beam ω₀ covers real-time mobile terminals 501 and 502(designated as real-time with a ring around each). Beam ω₁, coversreal-time terminals 503 and 504. Beam ω₂ covers real-time mobileterminal 505.

In FIG. 6, the three beams cover all the mobile terminals. Beam ω₀covers mobile terminals 501, 502, 601, 602, and 603. Beam ω₁, coversmobile terminals 503, 504, 604, 605, and 606. Beam ω₂ covers mobileterminals 505, 607, 608, and 609.

For simplicity in the temporal-spatial equalizer example of FIGS. 5 and6, users are shown to have either have voice or data service. However,this is not a requirement and a user can have both voice and dataservices simultaneously. A user who simultaneously uses both classes ofservices is counted as the member of voice population (real-time) aswell as that of data user population (non-real-time). Also, in order tosatisfy the delay requirements of the sessions, particularly thereal-time ones, the network may or may not use an admission controlpolicy to properly limit that the number of ongoing sessions, real-time,as well as non-real-time when necessary, per frequency channel.

Load Equalizer with Packet Steering

In a wireless environment, benefits found in reducing the powerconsumption of each mobile. In order to do so, the load equalizer may beused in conjunction with packet steering approach as known in the art onthe uplink beam. Using packet steering, after receiving the request tosend (RTS) message from a mobile and granting transmission right to it,the load-equalizing smart antenna directs a point-to-point receive(uplink) beam, i.e., as narrow a beam (e.g., 15°±5°) or as narrow as theantenna array can create, to the location of the mobile. After receivingthe packet from the mobile, it may send its acknowledgement (ACK) packeton the downlink beam while restoring the uplink beam to its normalbeam-width set by the load equalizer so that it can hear RTS packets ofall mobiles assigned to a frequency channel. The smart antenna repeatsthis process after granting the transmission right to a mobile.

Components of the Temporal-Spatial Load Equalizer

FIG. 7 shows an illustrative architecture that may be used inconjunction with a load-equalizing smart antenna. The architecture mayinclude a smart antenna system 704 having an antenna 701 and antennacontroller 702. Antenna controller 702 interacts with network 703.Network 703 may include transport, control and management entities. Forsimplicity, FIG. 7 shows those elements of the network that interactwith the controller 702 (including Outbound SIP Proxy 706 that isconnected to a SIP Server 705, which is in turn connected to profileserver 707. Profile server 707 may be connected to resource manager 708,which may be connected to policy server 709. The arrangement of elementsin network 703 is for example only. Other relationships may be used aswell.

The controller 702 may include a SIP message processor (SMP) 710 thatexchanges information with outbound SIP proxy 706 and database updateengine 711. Controller 702 may also include a database update engine 711that exchanges information with resource manager 708, SMP 710, andpolicy server 709 and stores information in location database 712.Controller 702 may further include a load equalizing (and control)engine 713 that exchanges information with location database 702.

Antenna 701 may include a spatial-temporal de-multiplexer 714 and aspatial-temporal multiplexer 716. Both may be connected to processor715. The antenna 701 may further include a multi-channel receiver 717connected to the de-multiplexer 714 and processor 715. The antenna 701may further include a multi-channel transmitter 719 connected to themultiplexer 714 and processor 715. The multi-channel receiver 717 andmulti-channel transmitter 719 may be connected to the antenna array 718.

Processor 715 computes (or captures necessary data for computation of)the direction of arrival (DOA) of users'mobile terminals and passes it(or them) to the load equalizing engine 713. The processor 715 may alsoreceive the beam-widths from the load-equalizing engine of thecontroller 702 (or controllers 702) and translate them into appropriateweight vector for steering the antenna beams from antenna 701 (orantennas 701). For each network 703, there may be one or morecontrollers 702 and one or more antennas 701. For each controller 702,there may be one or more antennas 701. Further, each controller 702 maybe connected to one or more networks 703.

The controller 702 obtains and processes information regarding theusers'locations and their services and turns the information intocontrol actions for steering the antenna 701 's beams in accordance withthe operator's policies. For instance, the load-equalizing engine 713may be a policy enforcement point (PEP) whose task is to use userslocation and services data to maximize the throughput of the smartantenna, i.e., it may realize the temporal-spatial load-equalizingapproaches described above. The load-equalizing (or in general, thecontrol) engine 713 represents a dynamic policy enforcement point thatcan enforce any operator's policies. The controller 702 may include thefollowing:

-   -   a. A SIP Message Processor (SMP) 710 that is call/session-state        processing engine.

The SIP Message Processor (SMP) 710 receives a copy of signalingmessages from and to users located within the coverage area of theantenna 701, processes/filters them to get (or update) informationregarding users and their services and sessions, and forwards theinformation to the database update engine 711 for updating informationin location database 712;

-   -   b. A standard (e.g., a SQL) location database 712 that contains        users locations, their ongoing sessions and types of services on        these sessions;    -   c. A load-equalizing engine 713 that uses data in the location        database 712 to realize the temporal-spatial load equalizing        heuristic set forth above. A policy enforcement point may        enforce the control policy prescribed by the policy server; and    -   d. A database update engine 711 that initializes and updates the        location database 712 according to the information received from        the SIP Message Processor (SMP) 710, and the processor 715 of        the antenna 701.

The controller 702 is shown as separate from antenna 701. Alternatively,controller 702 may be integrated with antenna 701. Further, controller702 may be integrated with outbound SIP proxy 706 in network 703 orsomewhere between network 703 and antenna 701 (e.g., integrating the SIPmessage processor (SMP) 710 with the outbound SIP proxy 706 and the restof its entities with the antenna 701. In general, the controller 702 maybecome an integral part of a mobile communication server (MCS).

User Services and Sessions

The following relates to relevant information regarding user'servicesand sessions and how controller 702 initializes location database 712,obtains relevant data, and updates location database 712.

User Data Object

Each user's mobile terminal may be identified by a user data object inthe location database 712 that contains all relevant information on thelocation of the terminal and ongoing sessions and services originatedfrom or terminated at the user's terminal. A user data object 801 mayinclude one or more of the following attributes as shown in FIG. 8:

-   -   a. The SIP URL of the user 802;    -   b. The IP address of user's terminal 803;    -   c. The MAC address of the user's terminal 804;    -   d. The location (and/or the azimuthal angle) of the user        terminal (absolutely or in relation to antenna 701) 805; and    -   e. The service types of ongoing sessions originated from the        user's mobile terminal or terminated on it, the SIP session        identifiers (Session IDs), as well as their corresponding        equivalent capacities 807.    -   f. Additional information may or may not be included as 808.

In general, the triplet comprising the MAC address of user's terminal,its IP address, and the user's SIP URL may be used to identify andupdate a user data object in the location database 712 of the antenna701. The MAC address of the terminal identifies it regardless of userservices and/or mobility patterns as well as network protocols forsupporting mobility. The MAC address may operate as one or more objectidentifiers in the location database 712 for associating user servicesand sessions to the location of the mobile terminal. The SIP signalingmessages identify a user's session by her/his URL and IP address. Thebody of the SIP REGISTER message may associate/map user URL and IPaddress with/to MAC address of her/his terminal. The SIP URL in thesession setup messages may associate a session with the user but notalways with her/his terminal due to the service mobility. For instance,a user may transfer an ongoing session from her/his mobile to anotherappliance (e.g., her/his office telephone) that does not necessarilyappear in the location database. In this case the IP address within theSIP RE_INVITE (or UPDATE) message may indicate that this session hasbeen transferred to another appliance and can be removed from the userdata object representing her/his mobile and its ongoing activities. Itallows the database update engine 711 to remove this session from theuser data object.

Initialization and Update of the Location Database

An attribute of the user data object that assists in a load equalizingantenna is the location or the azimuthal angle of the location of theuser's terminal. The angle may be detected directly or determined fromabsolute location identification information (GPS, triangulation, orhyperbolic location identification information). An antenna system mayuse received signals in conjunction with either a position location orDirection of Arrival (DOA) estimation algorithm as known in the art toobtain the azimuthal angle of the user (i.e., terminal) location. Threeissues exist with using DOA information in a smart antenna:

-   -   a. How is the location database 712 initialized at the start up        of the antenna system?    -   b. How does the controller 702 ensure that the load equalizing        (control) engine's 713 dynamic adjustment of the beam-widths and        their angles leaves no in-active users/terminals left out of the        system coverage and service for an unacceptable (or indefinite)        period of time?    -   c. How are the locations, service types and equivalent        capacities of sessions obtained and stored in location database        712?

To address the first issue, the antenna's beam-widths and their anglemay be initialized such that they cover the whole area at the systemstartup time. The load equalizing (control) engine 713 assigns initialbeam-widths to ω_(k)=π/N, 0≦k<N. For instance, a load-equalizing enginestarts a three beam antenna with ω₀=ω₁=ω₂=ω₃, and starts enforcing theload-equalizing methodology as soon as the initialization interval isexpired. The exact value of the initialization interval duration dependson how long it takes the DOA algorithm to determine the locations of allactive terminals within the coverage of the system.

The database update engine 711 then initializes users'data objects withat least one of their locations and MAC addresses, while setting theremaining objects to “NULL” until the database update engine 711receives information on the URLs, IP addresses, and Session IDs andtraffic descriptors from the SIP Message Processor (SMP) 710. Databaseupdate engine 711 processes the information received from the SIPMessage Processor (SMP) 710 to derive and update the remainingattributes of a user data object.

To address the second issue, i.e., allowing users to rejoin the systemwhen they become active again after a period of silence is similar tothat of the first question, with a difference that the latter is aperiodic process, while the former may be a task that is performedrelatively infrequently. In other words, the load equalizing (control)engine 713 of an antenna 701 that has N beams periodically (forinstance, every T_(p) sec) suspends its load-equalizing beam forming,and creates beams of width ω_(k)=π/N, 0≦k<N, to sweep the whole coveragearea and instate (or re-instate) all the active users in the locationdatabase. As in the initialization task, the length of the suspensiontime depends on the DOA algorithm. The trade-offs in the choice of thedatabase updating period, T_(p), are that it should be 1) much largerthan the temporal-spatial frame size T so that the impact of theseupdates on the performance of the load-equalizer is relativelynegligible, and 2) small enough to ensure that chance of locking out anoff-hook user is minimal.

Alternatively, another beam may be created (from the same antenna arrayor another antenna array) to sweep the area to check for all, new, orrejoining mobile terminals.

To address the third issue, the database update engine 711 may modifythe database upon reception of new locations, sessions, and servicesinformation from either the SIP Message Processor (SMP) 710 or theprocessor 715 of the antenna 701.

When the database update engine 711 receives data from either the SIPMessage Processor (SMP) 710 or the processor 715 of the basic smartantenna, the database update engine 711 processes the information (e.g.,calculates the equivalent capacity of the session) as needed, andupdates the corresponding user data object, if the object already existsin the database. Barring abnormal conditions, the object may alreadyexist in the database. Otherwise, it creates a new user data object inthe database whose identifier is used to access it. The identifier mayor may not be the MAC address of the “new” user's terminal.

The database update engine 711 may expunge the stale user data objectsif and when needed. For instance, old objects (a few minutes or hoursold with no subsequent updates) may no longer be relevant. If theantenna does not receive signal from a user mobile for an extendedperiod of time, it considers her/his user data object stale. In thisregard, a user data object may be considered stale, if either the userterminal is broken or it has not renewed its registration for a longperiod (as specified by the operator's policies) of time.

Obtaining Information on Users Sessions and Services

The controller 702 maintains information regarding a user, his/herterminal MAC and IP addresses, and ongoing sessions and services fromSIP signaling messages. With regards to IEEE 802.11 WLANs, a terminalusually registers with the access point first before being able to sendinformation. Thus, the MAC address and location attributes of a userdata object usually appear in the location database before the others.

The attributes of a user data object that may be obtained from SIPmessages are user SIP URL, IP address and corresponding MAC address ofher/his terminal, “Session-IDs” of its ongoing sessions, and theirservice requirements. Alternatively, these may be derived from othersources. The URL and terminal addresses at the MAC and IP levels can beobtained during SIP registration message flow, while the informationregarding ongoing sessions and their services can be derived from theSIP call setup message exchange. The SIP outbound proxy 706 is in theroute of signaling messages of mobile originated and mobile terminatedsessions of users within the coverage area of the antenna 701. It copiessignaling messages to and from users within the coverage area of theantenna 701 to the SIP Message Processor (SMP) 710. The SIP MessageProcessor (SMP) 710 filters these messages to obtain the requiredinformation for passing to the database update engine 711.

The SIP Message Processor (SMP) 710 ensures that the user data objectsof the location database contain correct and up to date informationregarding the URLs, IP addresses, and MAC addresses of users. The SIPMessage Processor (SMP) 710 may perform this and other tasks through oneor more of the following:

-   -   a. Upon reception of SIP REGISTER message from the outbound SIP        proxy 706, the SIP Message Processor (SMP) 710 processes the        message, both the header and the body, to obtain at least one of        the user URL, its terminal IP address, its MAC address, as well        as the registration Session-ID. The registration session ID,        user URL and IP address of his/her terminal are available in the        SIP REGISTER header. The MAC address may be obtained from the        REGISTER message body.    -   b. When mobile IP provides terminal mobility, the user NAI        (i.e., the Home IP address of the user) may be located in the        CONTACT field of the SIP register message. Particularly, in the        case of cross appliance service mobility, after the change of        appliance, the CONTACT field may be set to the NAI of the        changed-to mobile terminal. Then, the database update engine 711        knows that the session does not any belong to the original        mobile terminal.    -   c. Upon the reception of the “200” OK message with the same        registration Session-ID, SMP forwards the MAC address, IP        address, and the URL to the DB update engine. The DB update        engine uses the MAC address to identify the user data object        whose SIP URL and IP address attributes should be updated.

The following describes the separation of resource and sessionmanagement in SIP and its implications. As is known in the art, the SIPspecifications separates resource management and session managementfunctions. As far as SIP is concerned, resource management is apre-condition for setting up sessions. Here, the request for setting upa session with a certain amount of resources cannot be completed untilresources are reserved, though SIP itself does nothing about gettingthese resources, and it is up to the end users to obtain necessaryresources. However, other protocols may permit the network to take amore active role in reserving the resources.

The message flow for setting up a basic session with a resourcepreconditions (e.g., a phone call) is shown in FIG. 9. Here, a callerfrom within the coverage area of the antenna is placing a call to acallee outside the coverage area of the antenna.

In step 901, a call starts with an INVITE message from the callercontaining an SDP (session description Protocol) PDU (Protocol DataUnit) in the body of the INVITE message. The SDP PDU contains within thebody of an INVITE message contains the service requirements of asession. The SDP PDU (shown as SDP1) contains the session mediainformation that informs the callee about the type and requirements ofthe service(s) that the caller terminal can support.

Next in step 902, the callee responds with a 183 session in progresscontaining an SDP PDU (shown as SDP2) indicating the capabilities of thecallee's terminal.

In steps 903 and 904, after receiving the “183” message, the caller andcallee exchange PRACK and OK messages. The acknowledgement messages arefollowed by a reservation period 905 in which the caller and calleereserve resources by their own means and protocols (e.g., RSVP, etc.).

When the reservation process is complete, the caller sends an UPDATEmessage 906 containing an SDP PDU (shown as SDP3) that describes themedia reservations in the caller to callee direction.

The callee sends a “200” OK message 907 that contains an SDP PDU (shownas SDP4) showing media reservation in the callee to caller direction.

The callee sends a ringing message 908 to the caller to alert the callerthat the callee is now ringing.

A pair of acknowledgement signals is exchanged as 909 and 910.

Then callee then indicates the call is connected in 911 and the calleracknowledges in 912 and the session starts. Finally, the caller sends anACK message to the callee, and the session begins in step 913.

The preceding message flow shows that the SIP Message Processor (SMP)710 processes the INVITE-SDP1 901, UPDATE-SDP3 906, and 200 OK-SDP4 907,and the final ACK 912 messages of the message flow to obtain informationregarding a session and its service. The SIP Message Processor (SMP) 710may or may not ignore all other call set up messages regarding each callthat are copied to it. The SIP Message Processor (SMP) 710 may processthe INVITE 901, UPDATE 906, 200 OK 907, and ACK 912 messages of eachcall as follows:

Upon the reception of each INVITE 901 from the outbound SIP proxy 706,SIP Message Processor (SMP) 710 processes the header of the INVITEmessage to get the Session-ID, caller's SIP URL and IP address, andcreates a temporary data object containing one or more of these data.

Upon receiving an UPDATE message with the same Session-ID from theoutbound SIP proxy 706, SIP Message Processor (SMP) 710 obtains themedia information from the SDP PDU within the UPDATE body. The SDP PDUmedia identifies the requirements of this session service in the uplinkdirection. The SIP Message Processor (SMP) 710 adds this session media(i.e., service requirements) on the uplink to the temporary data objectwhose Session-ID attribute is identical to the Session ID of the UPDATEmessage.

Upon reception of the subsequent 200 OK 904 with the same Session-ID,the SIP Message Processor (SMP) 710 obtains the media information fromthe SDP PDU within the body that specifies the service requirements ofthe session on the downlink. Then, the SIP Message Processor (SMP) 710includes this downlink session media information into the temporary dataobject whose Session ID attribute is the same.

Finally, when the SIP Message Processor (SMP) 710 receives a subsequentACK with the same Session-ID, it forwards this temporary data object tothe database update engine 711.

The database update engine 711 processes the forwarded temporary dataand updates the corresponding user data object 801, accordingly. Thedatabase update engine 711 receives the temporary data object containingone or more of a URL, an IP address, a Session ID, and uplink anddownlink media information. The database update engine 711 sends amessage to the resource manager that contains the Session ID as well asthe uplink and downlink media information of the session. Depending onthe resource management scheme of the network, the resource managereither computes the equivalent capacity and sends it to the databaseupdate engine 71 1, or sends the traffic descriptors of the session'suplink and downlink media to the database update engine 711 to computethe equivalent capacity itself. Then, the database update engine 711uses the MAC address, URL, and IP address to uniquely identify andupdate the corresponding user data object in the location database.

The control system and technique may further be applied to other arenasas well. Further, one may standardize code points for the Type andSubtype fields of the announcement MAC_PDUs of a WLAN that ensure properframing on the uplink of a load equalizing smart antenna. The loadequalizing smart antenna may be used with other similar antennas andconventional (non-load-balancing) antennas.

Session Admission Control in Packet Networks

The antenna and control system may control load through selectivesession admission in packet networks. Session (or call) admissioncontrol decides whether to accept or reject a request of setting up anew session in accordance with a network's traffic management policies.Since a network supports different classes of services with distinctcapacity needs and QoS requirements, an admission control policygenerally attempts to establish fair blocking among the service classes,assure that sufficient network resources are available for each admittedsession, and maintain an acceptable utilization level for the overallpool of network resources.

The traffic management of packet (ATM or IP) networks has been studiedextensively. Numerous admission control, scheduling, flow control,policing and shaping techniques exist and may function with the antennaload-balancing system described herein. Two approaches are described.These approaches are session admission control using either “equivalentcapacity” of a session, or the “admission region” of a node in thenetwork.

Admission Control Using Equivalent Capacity

For admission control using equivalent capacity, the network uses atraffic descriptor of a session and its QoS requirements to estimate theamount of capacity that is required (referred to as equivalent capacity)for supporting the session. Various analytical expressions forderivation of the equivalent capacity have been proposed. The equivalentcapacity of a session may be chosen such that, for a given buffer sizeof X packet per session at the access interface, the packet loss ratioof the session on the access link does not exceed a specified value βagreed upon in the service layer agreement of the session. The primaryQoS constraint on the performance of real-time services is that packetdelay should not exceed an upper bound T. Thus, in order to satisfy it,the maximum buffer size per a real-time session should be X≦0.5┌T/μ┐,where μ is the mean service (access plus transmission) time of areal-time packet on the frequency channel.

If the peak rate of the traffic on the i-th session is R_(p) ^((i)), itsmean rate R_(a) ^((i)), and its mean burst length δ_(i) ⁻¹. Assumingthat the traffic activity on the i-th session conforms to a two-stateMarkov chain model, and using the results of Anick et al. (D. Anick, D.Mitra, and M. M. Sondhi, “Stochastic Theory of Data Handling System withMultiple Sources”, Bell System Technical Journal (BSTJ), Vol. 61, No. 8,October 1982) with a simple fluid approximation of the session traffic,Guerin, et al. (R. Guerin, H. Ahmadi, and M. Naghshineh, “EquivalentCapacity and Its Application to Bandwidth Allocation in High-SpeedNetworks”, IEEE Journal on Selected Areas of Communications, Vol. 9, No.7, September 1991) arrives at the following expression for equivalentcapacity, C₁, of the i-th session:${C_{i} \cong \frac{{{{\alpha\delta}_{i}^{- 1}\left( {1 - \rho} \right)}R_{p}^{(i)}} - X + \sqrt{\left\lbrack {X - {{{\alpha\delta}_{i}^{- 1}\left( {1 - \rho_{i}} \right)}R_{p}^{(i)}}} \right\rbrack^{2} + {4X\quad{\alpha\delta}_{i}^{- 1}{\rho_{i}\left( {1 - \rho_{i}} \right)}R_{p}^{(i)}}}}{2{{\alpha\delta}_{i}^{- 1}\left( {1 - \rho_{i}} \right)}}},$[991 where α=−Ln(β) and ρ_(i)=R_(a) ^((i))/R_(p) ^((i)). It is worthnoting that as ρ_(i)→1, e.g, a voice telephony session, then C_(i)→R_(p)^((i)), i.e., the equivalent capacity of a constant bit rate sessionequals its peak rate.

The network admits the request for setting up a session if the freecapacity on the access channel (link/medium) exceeds the equivalentcapacity of the requested session, i.e., Σ_(j)C_(j)≦C, where C is thechannel capacity. It is worth noting on a multiple access share mediumchannel such as an 802.11 WLANs, C represents the maximum throughput ofthe media under “nominal” operation of its MAC protocol.

Admission Control Using Admission Region

For an admission control using admission region approach, the networkuses the admission region “maps/curves” as guidelines to decide whetherto accept or reject session set-up requests in packet networks. Thesemaps/curves may be stored in the network elements such as switchingnodes, smart antenna controllers, or elsewhere or not stored in thenetwork yet access from the network. An admission region is a map/curvewhose points represent the number of simultaneous sessions of differentservices classes that can be supported by the channel or node.

The admission region maps are usually obtained off-line, throughmeasurement, simulation, or analysis, assuming a predetermined number ofservice classes in the network in the network. This approach may beeffective for small networks with limited number of service classes.

For example, in case of an antenna system supporting only voice and besteffort data services, one needs to measure (or derive) the admissionregion of each frequency channel as a function of its beam-width. Theadmission region is a curve that shows the number of simultaneous voicesessions that a system can support versus the volume of data trafficpresent in the system. One benefit of using an admission control usingan admission region approach is that the admission region reflects thenominal operation of the MAC protocol.

1. A process for equalizing traffic among two or more beams from anarray antenna comprising the steps of: determining the capacity desiredfor each one of mobile terminals in an area covered by said two or morebeams; determining the location of said mobile terminals; allocatingsaid two or more beams so that said beams service said terminals; anddirecting a first of said two or more beams to service said terminals,where at least one of said beams services a number of terminals whosecollective capacity is at least 1/N th of the total capacity desired bythe terminals to be serviced by said beams and where N is the number ofbeams.
 2. The process according to claim 1, said allocating step furthercomprising the step of: adding terminals to a first beam of said two ormore beams until a maximum width of said first beam has been reached. 3.The process according to claim 1, said allocating step furthercomprising the step of: adding terminals to a first beam of said two ormore beams until the desired capacity of terminals in said first beammeet or exceed 1/Nth of the total capacity desired by the terminals tobe serviced by said two or more beams.
 4. The process according to claim1, wherein said allocating step allocates said beams among saidterminals based on desired capacity of non-real-time information.
 5. Theprocess according to claim 1, wherein said allocating step allocatessaid beams among said terminals based on desired capacity of real-timeinformation.
 6. The process according to claim 1, wherein saidallocating step allocates said beams among said terminals based ondesired capacity of both and real-time and non-real-time information. 7.The process according to claim 6, said allocating step furthercomprising the steps of: separating a time frame into a real-timeportion and a non-real time portion; allocating said beams during saidreal-time-portion to handle said real-time information; and allocatingsaid beams during said non-real-portion to handles said non-real-timeinformation.
 8. A system for equalizing traffic among two or more beamsfrom an array antenna comprising the steps of: means for determining thecapacity desired for each one of mobile terminals in an area covered bysaid two or more beams; means for determining the location of saidmobile terminals; means for allocating said two or more beams so thatsaid beams service said terminals; and means for directing a first ofsaid two or more beams to service said terminals, where at least one ofsaid beams services a number of terminals whose collective capacity isat least 1/N th of the total capacity desired by the terminals to beserviced by said beams and where N is the number of beams.
 9. The systemaccording to claim 8, said means for allocating adds terminals to afirst beam of said two or more beams until a maximum width of said firstbeam has been reached.
 10. The system according to claim 8, said meansfor allocating step adds terminals to a first beam of said two or morebeams until the desired capacity of terminals in said first beam meet orexceed 1/Nth of the total capacity desired by the terminals to beserviced by said two or more beams.
 11. The system according to claim 8,wherein said allocating means allocates said beams among said terminalsbased on desired capacity of non-real-time information.
 12. The systemaccording to claim 8, wherein said allocating means allocates said beamsamong said terminals based on desired capacity of real-time information.13. The system according to claim 8, wherein said allocating meansallocates said beams among said terminals based on desired capacity ofboth and real-time and non-real-time information.
 14. The systemaccording to claim 13, said allocating means further comprising: meansfor separating a frame into a real-time portion and a non-real timeportion; means for allocating said beams during said real-time portionto handle said real-time information; and means for allocating saidbeams during said non-real portion to handles said non-real-timeinformation.
 15. A computer-readable medium comprising a data structure,said data structure comprising: a first portion including a SIP URL of aterminal; a second portion including a location of said terminal,wherein said location information stored in said second portion is usedto allocate a beam to service a terminal identified by the informationin said first portion.
 16. The computer-readable medium according toclaim 15, further comprising: a third portion storing an IP address ofsaid terminal.
 17. The computer-readable medium according to claim 15,further comprising: a third portion storing a MAC address of saidterminal
 18. The computer-readable medium according to claim 15, furthercomprising: a third portion storing a service type of at least oneon-going session of said terminal
 19. A system for equalizing trafficamong beams comprising: an antenna having beams that service terminals;a controller that controls said antenna, said controller having a loadequalizing engine that allocates said beams based on the location ofsaid terminals and capacity desire by said terminals.
 20. The systemaccording to claim 19, said control further comprising: a locationdatabase that stores the location of a terminal.
 21. The systemaccording to claim 19, said control further comprising: a locationdatabase that stores the type of service or services of on-goingsessions of a terminal.